Question 1: Define dynamic equilibrium in the context of a reversible chemical reaction.

Answer: Dynamic equilibrium occurs when the rate of the forward reaction equals the rate of the reverse reaction, resulting in no net change in the concentrations of reactants and products.

Question 2: Explain how the principle of Le Châtelier's principle applies when a system at equilibrium is subjected to a change in temperature.

Answer: According to Le Châtelier's principle, if the temperature of an equilibrium system is increased, the system will shift in the direction that absorbs heat (endothermic reaction). If temperature is decreased, it shifts to release heat (exothermic reaction).

Question 1: Calculate the equilibrium constant (Kc) for the reaction: N₂ + 3H₂ ⇌ 2NH₃, given that at equilibrium, [N₂] = 0.2 mol/dm³, [H₂] = 0.6 mol/dm³, and [NH₃] = 0.4 mol/dm³. Use the formula Kc = [products]/[reactants].

Answer: Kc = [NH₃]² / ([N₂] × [H₂]³) = (0.4)² / (0.2 × (0.6)³) = 0.16 / (0.2 × 0.216) = 0.16 / 0.0432 ≈ 3.70

Question 1: Describe a suitable method to investigate the effect of concentration changes on the position of equilibrium in the reaction: CO(g) + Cl₂(g) ⇌ COCl₂(g). Include variables to control and safety precautions.

Answer: The method involves preparing a sealed reaction vessel with known concentrations of CO and Cl₂ gases. By varying the initial concentrations of either reactant and measuring the amount of COCl₂ formed at equilibrium using gas chromatography or spectrophotometry, students can observe shifts in equilibrium. Variables to control include temperature, pressure, and initial amounts. Safety precautions include handling gases carefully in a well-ventilated area, using appropriate gas detectors, and wearing safety goggles and gloves.

Question 1: A reaction at equilibrium shows that increasing the pressure causes the concentration of the gas phase reactant to decrease. What does this suggest about the number of moles of gas on each side of the balanced equation?

Answer: It suggests that the side of the reaction with fewer moles of gas is favoured when pressure increases, indicating that the reaction shifts towards the side with fewer gas molecules.

Question 1: Describe how the Haber process for synthesising ammonia relies on the principles of dynamic equilibrium to optimise production. Include considerations of temperature, pressure, and catalyst.

Answer: The Haber process operates under high pressure and moderate temperature to favour ammonia formation, which is a reversible reaction. A catalyst (iron) is used to speed up the attainment of equilibrium. The process is carefully controlled to maintain a steady state where the forward and reverse reactions occur at equal rates, maximizing ammonia yield while preventing the reaction from going to completion, which would reduce efficiency.

Question 1: Explain how Le Châtelier's principle can be used to increase the yield of a product in an industrial reversible reaction. Include an example involving temperature or pressure changes.

Answer: Le Châtelier's principle states that if a system at equilibrium is subjected to a change in conditions, the system will adjust to minimise that change. For example, increasing pressure shifts the equilibrium towards the side with fewer moles of gas, increasing product yield. Similarly, decreasing temperature favours the exothermic direction. By manipulating temperature and pressure, industries can optimise reaction conditions to maximise product formation while maintaining a dynamic equilibrium.